JPH0136979B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a wafer is loaded in an ultra-high vacuum chamber, and this wafer contains Ga, Al, and As in the form of molecular beams.
The present invention relates to a wafer mounting structure in a molecular beam epitaxial apparatus that grows a film by injecting a material such as the like, and particularly relates to a wafer mounting structure in which a wafer is attached to a molybdenum block.

A molecular beam epitaxial apparatus is generally designed in principle as shown in FIG. In FIG. 1, reference numeral 1 indicates a chamber with an ultra-high vacuum inside, 2 indicates a GaAs wafer loaded in this chamber 1, and 3
4 is a heater for heating the wafer, 4 is a material supply source such as Ga, Al, As, etc. that is incident on the wafer 2 in the form of a molecular beam;
5 is a heater wire, 6 is a shutter 7 is an electron gun, 8 is a mass spectrometer, and 9 is an RHEED (abbreviation for high-speed reflection electron diffraction) screen. Therefore, the molecular beam source in this epitaxial apparatus is composed of the material supply source 4, the heater wire 5, and the shutter 6. FIG. 2 is a partially cutaway perspective view of the chamber 1. FIG. In FIG. 2, reference numeral 9 indicates the shutter 6.
10 is a liquid nitrogen container; 11 is an operating knob for directing the wafer 2 loaded into the chamber 1 from the wafer loading hole of the chamber 1 toward the molecular beam incident side. In such a molecular beam epitaxial apparatus, the thickness of the film grown on the wafer 2 can be controlled with high precision.
As shown in Fig. 3, the molybdenum block 13
It is loaded into the chamber 1 while being attached to the surface 14 of the chamber 1 with an attaching material 15 such as indium interposed therebetween. On the other hand, inside the chamber 1 is a member 1 that supports the molybdenum block 13 in the loading position.
6, heater 3, and thermocouple 17 as a temperature sensing element.
and is provided. Therefore, when the molybdenum block 13 is loaded in a predetermined position in the chamber 1, the heater 3 and the thermocouple 17 are arranged on the back surface 18 side of the molybdenum block 13.
This thermocouple 17 detects the temperature of the wafer 2 heated by the heater 3, and provides its detection output to a temperature control circuit (not shown). Further, this temperature control circuit controls the heating operation of the heater 3 in response to this detection output, so that the wafer 2 is always maintained at a temperature of about 550 to 700 degrees Celsius.

By the way, the thermal radiation coefficient of molybdenum block 13 is 0.28, whereas
That of the GaAs growth layer is 0.7. Also, on the surface of the molybdenum block 13 except for the wafer 2,
A growth layer of GaAs is generated. Therefore,
The wafer temperature at the start of film growth decreases as the GaAs growth layer is formed on the surface 14 of the molybdenum block 13, and decreases by 40 to 50 degrees Celsius or more compared to the temperature at the end of growth. I'll come. However, the thermocouple 17 uses the local temperature of the molybdenum block 13 as the wafer temperature. Therefore, even though the actual wafer temperature has significantly decreased, since the local temperature of the molybdenum block 13 is constant, there is a risk that the wafer temperature may be controlled assuming that the wafer temperature is also constant. Such unstable temperature control has the disadvantage that it is not possible to grow GaAs on the wafer that satisfies predetermined characteristics. In order to solve these difficulties, the present applicant has proposed the invention ``Wafer mounting structure for molecular beam epitaxial apparatus'' in Japanese Patent Application No. 58-160071 (Japanese Unexamined Patent Publication No. 60-51696). In the invention according to this proposal, as shown in FIG. 4, a shielding plate 19 (adhesion prevention plate) is installed on the molybdenum block 13 so as to cover the surface of the molybdenum block 13 except for the part to which the wafer is attached. The shielding plate 19 prevents film growth material incident in the form of molecular beams from adhering to the surface. Therefore, although the invention proposed by the present applicant has solved the conventional drawbacks, since the shielding plate 19 is located above the surface of the wafer 2, the shielding plate 19 is located above the surface of the wafer 2, so that during the growth of the wafer 2 on the molybdenum block 13, It becomes difficult to observe the surface condition of the molybdenum block 13.
A new problem has arisen in that it becomes difficult to attach the wafer 2 to the wafer 2.The present invention aims to solve the problems of the conventional example described above, as well as the problems of the invention proposed by the present applicant. purpose.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. FIG. 5 is a sectional view of essential parts of an embodiment of the present invention, and parts corresponding to those in FIGS. 3 and 4 are given the same reference numerals. In Figure 5, 2 is
A GaAs wafer, 3 a heater, 13 a molybdenum block, 15 an attachment member, 16 a support member, 17 a thermocouple, 19 an adhesion prevention plate, and 20 a screw. Here, this adhesion prevention plate 19 has a molecular beam entrance window 21 formed corresponding to the wafer sticking part 22 on the molybdenum block 13, and has a molecular beam entrance window 21 formed corresponding to the wafer sticking part 22 on the molybdenum block 13, and the molybdenum block 1 except this wafer sticking part 22.
This is to prevent the material for film growth, which is applied in the form of a molecular beam, covering the surface 14 of 3 from adhering to the surface. The configuration up to this point is the same as that shown in FIG. 4, and therefore the drawbacks of the conventional example described above are solved.

What should be noted in this embodiment is the structure of the molybdenum block 13. That is, the wafer attachment portion 22 of this molybdenum block 13 is formed in a raised platform-like manner facing the molecular beam incidence window 21 formed in the adhesion prevention plate 19, and the surface on which the wafer 2 is attached is exposed to molecular beams. It approaches close to the inner surface of the entrance window 21. Therefore, when the wafer 2 is attached to the surface of the wafer attaching portion 22, the surface of the wafer 2 protrudes from the surface of the adhesion prevention plate 19 toward the above-mentioned molecular beam source side.

Therefore, when observing film growth on this wafer 2, since the surface of the wafer 2 protrudes beyond the surface of the adhesion prevention plate 19, the incident electrons and scattered electrons of RHEED will be blocked by the adhesion prevention plate. The observation can be easily carried out from the screen 9 without the molybdenum block 13 of the wafer 2.
It is also possible to easily attach the paper to the paper, thereby solving the problems of the above-mentioned invention proposed by the present applicant.

As described above, according to the present invention, a wafer stuck to the wafer sticking part on the surface of a molybdenum block is loaded into an ultra-high vacuum chamber, and a wafer stuck to the wafer sticking part on the surface of a molybdenum block is loaded into the chamber. It is applied to a molecular beam epitaxial device that is equipped with a heater and a temperature sensing element located on the back side to detect the heating temperature of the wafer. has a line entrance window, and
An anti-adhesion plate is placed on the molybdenum block to cover the surface of the molybdenum block except for the wafer attachment area and to prevent the material for film growth incident in the form of a molecular beam from adhering to the surface. The wafer attachment portion on the block is formed into a table shape in the direction of the molecular beam incidence window, and when a wafer is attached to the table-shaped wafer attachment portion, the surface of the wafer protrudes from the surface of the adhesion prevention plate toward the molecular beam source. Therefore, this adhesion prevention plate prevents the film growth material incident in the form of molecular beams from adhering to the surface of the wafer except for the wafer, and further prevents the wafer attached to the wafer attachment part on the molybdenum block. Since it is located above the mounting plate, it is possible to easily attach a wafer to the attachment portion and observe the film growth on the wafer.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a molecular beam epitaxial device used to explain the principle of the device, FIG. 2 is a partially cutaway perspective view of the chamber of this device, FIG. 3 is a cross-sectional view of a conventional example, and FIG. FIG. 5 is a cross-sectional view of an apparatus that solves the problems of the conventional example, and FIG. 5 is a cross-sectional view of an apparatus according to an embodiment of the present invention. 1 is the chamber, 2 is the wafer, 3 is the heater, 13
17 is a molybdenum block, 17 is a thermocouple, 19 is an anti-adhesion plate, 21 is a window, and 22 is a wafer attachment part.

Claims (1)

[Claims] 1. A wafer attached to the wafer attaching portion on the front surface of a molybdenum block is loaded into an ultra-high vacuum chamber, while a wafer attached to the wafer attaching portion on the front surface of the molybdenum block is placed inside the chamber. This device is applied to a molecular beam epitaxial device that is equipped with a heater and a temperature sensing element that detects the heating temperature of the wafer. and an adhesion prevention plate is provided on the molybdenum block to cover the surface of the molybdenum block except for the wafer attachment area and to prevent a film growth material incident in the form of a molecular beam from adhering to the surface. The wafer attachment part on the molybdenum block is formed into a table-like shape in the direction of the molecular beam incidence window, and when a wafer is attached to the table-shaped wafer attachment part, the surface of the wafer is closer to the molecular beam source than the surface of the adhesion prevention plate. Wafer mounting structure of molecular beam epitaxial equipment protruding from the side.